Dryer control apparatus



J. LIEBERMANN DRYER CONTROL APPARATUS Oct. 30, 1962 2 Sheets-Sheet 1Filed Sept. 8, 1959 ATTORNEY.

Oct. 30, 1962 J. LIEBERMANN DRYER CONTROL APPARATUS 2 Sheets-Sheet 2Filed Sept. 8, 1959 A 0 3 4 m 4 5 6 (3A A w 1. i w A w a a v w a a a A Ifii I I I M 0% i a A;

ATTORNEY 3&60591 DRYER CONTROL APPARATUS John Liebermann, Columbus,l1io, assignor to Rance Incorporated, Columbus, Ohio, a corporation of(Bhio Filed Sept. 8, 1959, Ser. No. 838,754 8 Claims. (Cl. 34-55) Thepresent invention relates to an improved dryer control apparatusparticularly suitable for use in controlling the operation of clothesdrying machines, although it could be embodied in control apparatus inmachines for drying other materials.

The principal object of the present invention is the provision of animproved control apparatus for drying machines, such as domestic typeclothes dryers, in which the drying cycle is terminated in response to apredetermined percentage reduction in weight of the material beingdried, whereby material can be accurately dried to a predetel-mineddegree less than bone dry.

In carrying out the invention, a drying machine is provided having amaterial containing element, such as a rotatable basket in which clothesare tumbled during the drying cycle, and which is arranged to bedeflected from a normal position by the weight of material placedtherein and to return toward the normal position as the material losesweight due to evaporation of the moisture. The drying machine isarranged to pass desiccating air over the material and the dryingoperation is automatically terminated by a control apparatus comprisinga first control member movable in opposite directions in a pathaccording to the amount of deflection and return of the materialcontaining element from its normal position and which cooperates with asecond control member to terminate the drying cycle, the second controlmember being moved by the deflection of the material containing elementbut through a different distance per unit of deflection of the elementthan the distance moved by the first control member, the second controlmemher being restrained from following the return movement of thematerial containing element so that as the material loses weight bydrying, the first control member moves to a given control positionrelative to the second control member to effect termination of thedrying cycle.

In the preferred form of the invention, the two control members compriseswitch contact members, one of which is movable directly by a weightresponsive means proportional to the deflecting and return movements ofthe material holding element while the other contact is moved by theweight responsive means through a reduction lever so that its movementis at a ratio of less than unity according to the movement of the firstcontrol member, and the second contact member is retained at theextremity of its movement responsive to the deflection of the materialcontaining element by a holding mechanism which is operated to releasethe second control member when the dried material is removed from theelement.

Other objects and advantages of the invention will be apparent from thefollowing description of a preferred embodiment, reference being made tothe accompanying drawings wherein FIG. 1 is a rear view of a domestictype clothes drying machine embodying the improved control apparatus,parts of the machine being broken away and shown in sectionsubstantially along line 11 of FIG. 2;

FIG. 2 is a view taken substantially along line 2-2 of FIG. 1;

FIG. 3 is a sectional view of the control apparatus;

FIG. 4 is a view similar to FIG. 3 but showing certain parts indifferent positions;

FIG. 5 is a view taken substantially along line 5-5 of FIG. 3; and

FIG. 6 is a schematic wiring diagram of the control system for theclothes dryer.

Although the invention could be employed to control machines for dryingvarious types of materials, it is here shown embodied in a domestic typeclothes drying machine, and referring to FIGS. 1 and 2 of the drawings,the machine shown is of conventional construction with the exception ofthe structure for supporting the drum in which the clothes to be driedare placed, The clothes dryer comprises a cabinet 10 having a shroudstructure 11 inside thereof for enclosing a perforated clothes receivingdrum 12. As is common, cabinet 10 has a circular front opening lllawhich is closed by a suitable door 19b, and basket or drum 12 has anopening 12a aligned with opening 10a for access to the drum. Anelectrical heating unit 13 is located within shroud 11, and is arrangedto heat air drawn into the shroud, after which the heated air isdirected through the perforations in the drum and exhausted through anoutlet 14 by operation of a blower 15, the air flow being indicated inthe drawings by arrows. The air enters cabinet 10 through louvers 16 andis directed over heater uni-t 13 by louvers 17. This type ofconstruction is conventional and further disclosure of details is notnecessary to the understanding of the invention.

Drum 12 is suspended so that the Weight of clothes placed thereindepresses or deflects the drum from a normal empty position, and forthis purpose the drum is rotatably suspended by an axle 20 which isjournaled in a lever 21 pivoted at one end on a shaft 22 supported by aU-shaped bracket 23 secured to the side wall of cabinet :10. A tensionspring 25 is attached at one end to lever 21 and the opposite end isattached to an eye 11a on the shroud wall so that the drum 12 and themembers carried therewith are counterbalanced by the spring.

Drum 12 is rotated by motor 19 through a drive mechanism which includesmotor pulley 19a drivingly connected by belt 19b to a pulley 26journaled on shaft 22 by a hub, not shown, integral therewith andattached to a second pulley 27 which is drivingly connected by a belt 23to a wheel .29 attached to drum axle 20. It is to be understood thatsuitable bearings are utilized for the journaled members so as toprovide relatively low friction turning of the parts. It will be seenthat as motor 19 operates blower 18, it also revolves clothes drum 12,and that the drum swings on lever 21 according to the change in weightof the drum and its contents.

The degree of depression of drum 12 depends upon the weight of clothesplaced therein, and the degree of return of the drum towards itsunloaded position is utilized to terminate the cessation of the dryingcycles, and for this purpose lever 21 has a downwardly projecting finger2111 which projects into a control casing of a control apparatus 32attached to a bracket 33 connected to the rear wall of cabinet 10.

Control 32 comprises a casing 320 having a wall 32b therein on which abar 34 is resiliently supported by two compression springs 34a at eitherend thereof, as seen in FIG. 5. Two guide posts 34b are attached to Wall32b and extend through springs 34a and openings in bar 34 to form guidesfor the bar and to locate the springs. Bar 34 is positioned to beengaged by finger 21a projecting through an opening in the top Wall ofthe control casing, and it will be apparent that the finger depressesthe control bar according to the weight of material placed in drum 12.

Bar 34 is arranged to actuate a switching mechanism comprising a firstcontact plate 36, supported by a coil spring 37 bottomed on wall 32b.Plate 36 has a post 36a thereon, preferably of a suitable dielectricmaterial, Which engages the underside of bar 34. A contact 36b isattached to plate 36 at one end thereof and is arranged to engage with acontact 38a attached to the underside of plate 38. By the arrangementshown, the elevation of plate 36 is controlled directly by the bar 34and its deflection and rise will be the same as that of drum 12.

The elevation of plate 38 is controlled by a lever which is pivoted on abracket 41 by a pin 40a, the plate being connected with the lever by apost 3811, which is preferably of dielectric material. The left hand endof lever 40 engages the underside of bar 34 and the point of engagementof post 38b with the lever, in the embodiment shown, is approximatelyone-third the distance between pivot 40a and the point of engagement ofthe lever with bar 34. By this arrangement, when bar 34 is depressedcontact plate 38 will be depressed but approximately two-thirds thedistance plate 36 is depressed, and contacts 36b and 38a will beseparated accordingly. It may be desirable to locate the point ofconnection of 381) with lever 40 at different locations to obtaindifferent degrees of dryness of the clothes, as will be understood asthe description proceeds.

Lever 40 is adapted to be latched in its ultimate depressed position bya ratchet toothed bar 43 having suitably shaped teeth 43a thereon whichare engaged by the right hand end of lever 49, which is tapered toengage the teeth. Latch bar 4 3 is pivoted to bracket 41 by a pin 43band is urged counterclockwise by a spring 44 interconnecting the bracketand the bar. The form of teeth 43a permit lever 40 to slide upwardlythereover as bar 34 depresses the left hand end of the lever 40 andlatch the lever in the position to which the lever is depressed so thatcontact plate 38 will remain stationary although bar 34 rises as theload in drum 12 is reduced.

Latch bar 43 is moved to lever releasing position when drum 12 is emptyby a projection 43c thereon which engages an upstanding cam surface 34cformed on bar 34, the cam surface having a surface 34d which slopestoward the left and which is brought opposite projection 430 when a loadis placed in drum 12 which permits spring 44 to move latch 43 intolatching position. Thus, the latch for retaining contact plate 38 in alowered position is effective only when drum 12 has a load therein.

Contact plate 36 is connected by a lead wire to a line L1 of aconventional three-wire 24-0 volt power supply system, and contact plate38 is connected by lead wire 51 to one terminal of a timer drivenswitching mech anism 53, described more fully hereinafter. Lead wires 50and 51 are partially enclosed in an insulated cover 3217 attached to thebottom of casing 32.

Referring now to the control system for the dryer, power is suppliedthrough the three-line, 240 v. system mentioned, which comprises linesL1, L2 and neutral line N. The circuit for heater 13 includes line L1,wire 55, central contact 56 of a conventional synchronous motordriventimer switch 57, contact 58 of the timer switch, wire 59 to one terminalof a commercially available thermostatic control 60, which is normallyclosed but opens when the air temperature reaches a predetermined highdegree and which recloses at a slightly lower temperature to therebymaintain a satisfactory drying temperature of the air passing throughthe clothes drum, then through heater 13 to line L2.

The circuit for motor 19 includes line L1, wire 54, contacts 56 and 62,wire 63 to one side of the motor, and wire 64 to line N.

The dryer timer switch 57 includes a cam 57a which is driven by suitablesynchronous motor 57b at a relatively slow rate, and the profile of thecam is such that when it is set to the on position, as by a manual knob57c, contacts 56, 58, and 62 are all closed to complete the heatercircuit and motor circuit 19.

The circuit for synchronous motor 57b includes line L1, contact 56, 62,wire 50, contacts 36b and 38a, Wire 51 to one side of the timer motor,and wire 65 to line N. Cam 57a has two depressions, one at 57d whichcauses contact 56 to drop from contact 58 while maintaining contact with62. A second depression 57c causes contact 62 to separate from contact56. The timer motor may be set to rotate the cam in a clockwisedirection from the rise portion to the left of depression 57d inapproximately eight minutes and to move the cam through depression 57ain approximately four minutes prior to opening of the blower circuit sothat the drum may rotate while cool air is drawn through the materialtherein to cool the clothes to a comfortable handling temperature afterwhich cooling operation the timer motor is discontinued by separation ofcontacts 56 and 62.

The operation of the control apparatus is as follows: A load of wetclothes is placed in drum 12 which de presses lever 21 causing contactmember 36b to be moved well below contact member 38a, as describedpreviously, which opens the circuit for timer motor 57b. Timer knob 570is then turned to the on position in which position contacts 56, 58 and62 are closed to energize the circuits for heater l3 and drive motor 19so that a drying cycle is commenced. Since contacts 36b and 38a areopen, the timer motor remains in the drying cycle starting position. Asmoisture is removed from the clothes during the drying cycle the weightof drum 12 is reduced, whereby lever 21 moves upwardly causing contact36b to move toward contact 38a, which is held stationary by lever 40latched with teeth 43a, and when contact 36b finally engages contact3841, due to reduction in weight of moisture in the material in thedrum, timer motor 57b is energized and rotates cam 57a to terminate thedrying cycle as described. The clothes are then removed from drum 12which causes bar 34- to actuate projection 43c to shift latch bar 43 andto release contact plate 38 so that the control apparatus 32 is incondition for the next cycle.

It will be seen that the degree of dryness is determined by theproprotionate degree of depression of contact plate 38 with respect tocontact plate 36 which is determined by the position of post 3811 alonglever 40. The smaller proportionate depression movements, resulting indrier clothes. The particular proportion desired for various types ofmaterials can be determined by experiment, after which the control isadjusted accordingly. While no adjustment is shown here for sake ofsimplicity, it is apparent that such provision could be readilyefiected.

By my invention the degree of dryness of wet clothes can be accuratelydetermined according to the percentage of moisture actually removedduring the drying cycle.

Although but one form of the invention has been disclosed, other forms,modifications and adaptations can be made, all falling within the scopeof the claims which follow.

I claim:

1. In a drying apparatus including a container for material to be driedand power means to effect drying of materials placed in said container,means to resiliently support said container whereby said container isdepressed from a normal elevation when a load is placed therein andreturns toward said normal position as the load is reduced, and controlmeans for said power means operative in response to a predeterminedupward return movement of said container comprising first and secondcontrol members arranged for cooperation with one another to terminate adrying cycle of said power means, the first of said members being movedaccording to movement of said container, the second of said membersbeing moved according to movement of said container but at aproportionately less degree per unit of movement of said container, andmeans to block movement of said second member in the direction of thereturn of said container towards its normal position so that the returnmovement will bring said first control member into cooperative relationwith said second control member to terminate the drying cycle.

2. In a drying apparatus including a material container and power meansto effect drying of materials placed in said container, means movableaccording to the weight of material in said container, control apparatusfor said power means including two members movable relative to oneanother and having control means thereon which are operative when inpredetermined relative positions to effect termination of a dryingoperation by said power means, one of said members being moved by saidmovable means through a given range of movement in one direction inresponse to a given weight of material in said container, means to movethe other of said members through a different range of movement in saidone direction in response to said movement of said movable means, andmeans to block movement of said other member in the opposite directionso that movement of said one member in said opposite direction willbring said control means into said predetermined relative positions.

3. Drying apparatus as defined in claim 2 including means to releasesaid other member for movement in the opposite direction in response tothe return of said container to said normal elevation.

4. In a drying apparatus including a material container and power meansto effect drying of materials placed in said container, means movableaccording to the weight of material in said container, control apparatusfor said power means including two contact members movable relative toone another and operative when engaged to effect termination of a dryingoperation by said power means, one of said contact members being movedby said movable means through a given range of movement in one directionin response to a given weight of material in said container, means tomove the other of said contact members through a different range ofmovement in said one direction in response to said movement of saidmovable means, and means to latch said other contact member againstmovement in the opposite direction so that the movement of said onecontact member in said opposite direction will effect engagement thereofwith said other contact member.

5. In a drying apparatus including a material container and power meansto effect drying of materials placed in said container, a lever forsupporting said container, means to counterbalance the weight of saidcontainer so as to move said container to a predetermined elevation whensaid container is empty, control apparatus for said power meansincluding two members movable relative to one another and having controlmeans thereon which are operative when in predetermined relativepositions to effect termination of a drying operation by said powermeans, one of said members being moved by said lever through a givenrange of movement in one direction in response to deflection of saidlever, a second lever operative to move the other of said membersthrough a different range of movement in said one direction in responseto the deflection of the first mentioned lever, and means to blockmovement of said second lever in the opposite direction, said controlmeans being operated upon movement of said one member in said oppositedirection through a distance equal to the difference in movements ofsaid two members in said one direction.

6. In a drying apparatus including a container for material to be driedand power means to effect drying of materials placed in said container,weight sensitive means having a range of movement corresponding to theweight of material in said container, control apparatus for said powermeans including first and second members movable relative to one anotherand having first and second contacts respectively connected theretowhich are operative when in a predetermined relative position to effecttermination of a drying operation by said power means, said first memberbeing moved by said weight sensitive means through a given range ofmovement in opposite directions according to the weight of material insaid container, means to move said second member by said weightsensitive means in one direction a distance corresponding to an increaseof weight in said container and at a different distance per unit ofmovement of said weight sensitive means than the movement of said firstmember by said weight sensitive means, and means to restrain movement ofsaid second member according to movement of said weight sensitive meansin response to a decrease in weight of material in said container,movement of said first member in response to a decrease in weight ofmaterial in said container and relative to the restrained second memberbeing effective to bring said first and second contacts into saidpredetermined relative position.

7. In a drying apparatus including a container for material to be driedand power means to effect drying of materials placed in said container,weight sensitive means connected to said container and comprising an armadapted to move in first and second directions through distanceproportionate to increases and decreases in weight of material in saidcontainer, a first electrical contact means connected in operativerelation with said arm to follow .the movements thereof, a secondelectrical contact means adapted to cooperate with said first contactmeans for controlling said power means to terminate said drying, levermeans connecting said second contact means in operative relation withsaid arm and adapted thereby to follow movements of said arm in saidfirst direction, said lever means providing a difference in rates ofsaid movements of said first and second contact means in following saidarm, whereby movements of said arm in said one direction serves to movesaid contact means out of cooperative relation with one another to adistance dependent upon said difference in rate and upon the initialweight of material in said container, and ratchet means associated withsaid lever means for releasably restraining said second contact meansagainst movement in said second direction, whereby movement of said armin said second direction an amount corresponding to the last mentioneddistance will bring said contact means into said cooperative relation.

8. A drying apparatus as defined in claim 7 and including cam meansconnected with said arm and operative to release said ratchet means uponmovement of said arm in said second direction to a positioncorresponding to an empty container.

References Cited in the file of this patent UNITED STATES PATENTS1,086,567 Stone Feb. 10, 1914 2,263,681 Hart Nov. 25, 1941 2,859,536McEwen Nov. 11, 1958

